Method of forming cartons



S. M. SILVER METHOD OF FORMING CARTONS Dec. 23, 1969 2 Sheets-Sheet 1 Filed Jan. 4, 1967 FIG.2

v JNVENTOR.

STANLEY MILTON SILVER Dec. 23. 1969 s. M. SILVER 3,435,003

METHOD OF FORMING CARTONS Filed Jan. 4, 1967 2 Sheets-Sheet 2 INVENTOR. STANLEY MILTON SILVER United States Patent 3,485,008 METHOD OF FORMING CARTONS Stanley Milton Silver, Blenheim St., London W. 1, England Filed Jan. 4, 1967, Ser. No. 607,216 Int. Cl. B65b 7/20, 51/02 US. CI. 53-47 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to four-sided, end-sealed, tubular cartons and, more specifically, to methods for forming such cartons and to the resulting product.

End-sealed tubular cartons, of the type to which the present invention relates, as heretofore produced, have the distinct disadvantage that their seals were frequently imperfect and had leaks through which any highly comminuted, finely powdered contents would sift, with resultant loss of contents and contamination of surrounding areas; a contamination that might present serious dangers when the contents are of a toxic character. Such leaks resulting in the sitting of the carton contents are generally due to two factors. One such factor is the incomplete adhesion of the inner dust flaps to the outer closure flaps, particularly at their marginal side edge portion, because of the tendency of such dust flaps to curl inwardly, away from the outer closure flaps, when moistened with adhesive; such tendency resulting from the fact that the dust flaps are formed with the grain of the paperboard running between their parallel edges. The other factor is that when the carton wall panels are folded into tubular form along the pre-formed fold lines, such fold lines do not always assume an exactly parallel relation to one another. This results in the distortion of the position of the dust flaps and closure flaps, to have their edges disposed at an angle to the walls of the carton, when folded into place, producing gaps or holes between such edges and the carton walls through which the contents may sift.

It is the object of the present invention, therefore, to

devise methods for sealing the ends of the cartons of the character described which will, firstly, inhibit the curling of the inner dust flaps when moistened with adhesive, to thereby attain greatly increased contact and adhesion between their surfaces and the overlying closure flaps to which they are adhered; and secondly, to at least partly seal, especially in the corners of the carton, any gaps that may be created between the parallel edges of the dust flaps and the adjacent side walls of the carton due to inaccurate folding of the carton blank.

It is another object of the present invention to devise methods of the character described that may be practiced on conventional, constant motion, carton sealing equipments, at their regular speed of operation and without any substantial or material alteration of such equipment; except for a minor addition thereto.

In the drawings:

FIG. 1 is a fragmentary plan view showing one end of a blank for a carton of the present invention;

FIG. 2 is an isometric view, on a large scale, showing the blank folded, glued and set up for sealing;

FIG. 3 is a schematic view showing the set-up carton 3,485,008 Patented Dec. 23, 1969 "Ice of FIG. 2 as passing through a constant-motion straightline carton-sealing machine;

FIG. 4 is a more or less diagrammatic section taken on line 4-4 of FIG. 3; and

FIG. 5 is an isometric view of the sealed end of the carton.

Generally stated, the invention consists in the application of a sealant material between the inner surface of one of the outer closure flaps and the dust flaps in such a manner that it will become disposed between the side edges of the dust flaps and the surface of the adjacent carton walls when the dust and closure flaps are pressed together, and progressively pinching such walls toward one another as the end forming flaps are progressively moved to be pressed to one another, to thereby inhibit inward curling of glue-wetted inner dust flaps and insure contact and adhesion between the edges of the dust flaps, the sealant, and the carton walls, to adhere the edges to the carton walls.

Referring now in greater detail to the accompanying drawings illustrating the methods of the present invention and the resulting product, the carton blank therein shown is of conventional type including front and rear wall panels, 10 and 12, each formed with an outer end wall forming flaps, 14 and 16, respectively, defined from wall panels 10 and 12 by fold lines, 15 and 17, and the end wall panels, 18 and 20, each formed with an inner dust flap, 22 and 24 respectively; and. a glue flap, 26, along one longitudinal edge of the blank. The dust flaps 22 and 24 are preferably of a height not greater than half the width of a panel 10 and 12, and the closure panels 22 and 24 are of a length greater than half the width of a wall panel 18 and 20, and preferably equal to the full width of such wall panels.

The folded and glued blank, erected in tubular form, is shown (FIG. 3) as moved for scaling, in vertical position, on a constant motion, straight line sealing apparatus of generally conventional type, between guide rails 26, with the front and rear walls 10 and 12 disposed parallel to the direction of movement in the apparatus, as indicated by the arrow.

As conventional, the erected carton in its initial position in the apparatus, shown at A, has its flaps 14 and 1-6 laterally outwardly offset, to horizontal position, while flaps 22 and 24 remain erected. The carton is then moved to position B, where dust flaps 22 and 24 are folded to horizontal position, to overlie the carton opening, also as conventional. The carton is then moved to position C, in the course of which movement an adhesive, 30, is applied to selected flaps for adhering one of the closure flaps, as 14, to dust flaps 22 and 2-4 and the other closure fiap to closure flap 14. Such adhesive may be in the form of a glue or a thermoplastic material. It may be applied to the upwardly facing surfaces of the outwardly offset closure flaps 14 and 16, as illustrated, or to the upwardly facing surfaces of the inwardly offset dust flaps 14 and 16; both practices being conventional.

When adhesive is applied to flaps 14 and 16 a thickened band, 32, thereof may be applied to the marginal portions of the flap edges adjacent to fold lines 15 and 17.

It will be understood that when a thermoplastic adhesive is used, it is applied to the blank before folding and it is merely reconstituted into adhesive state at position C by the application of the conventional heated knives.

Such thickened band of adhesive 32, when in glue form, may be applied in any one of a number of ways, as by suitably notching the wiping or doctor blade of the gluer (not shown) so as to leave a thicker layer of adhesive on the appropriate edge of each of the gluing drums 33, or by the use of a second set of gluing drums in tandem with the drums 33. Preferably the band of thicker layer of adhesive may be so applied that it slightly overlaps the edges of those flaps to which it is applied, closest to fold lines 15 and 17.

When adhesive or glue is applied to flaps 14 and 16, a narrow band of glue may at the same time be applied to the marginal portions of the side edges of dust flaps 22 and 24, to provide an excess of glue along these portions on the closing of the flaps 14 and 16.

Thereafter, the carton is moved towards position D, in the course of which movement the flap 14 is plowed into horizontal position to overlie the horizontally offset inner dust flaps 22 and 24 and the adhesive-coated closure flap 1-6 is then plowed to overlie dust flap 14. From this position, instead of having the flaps pressed against one another to form the carton seal, as is conventional, the present invention provides for the gradual compression or pinching of the front and rear panels and 12 slightly towards one another, at a point immediately adjacent the fold lines and 17, to inhibit the inner movement or curling of dust flaps 22 and 24. Such pinching may be accomplished by applying to the inner surfaces of guide rails 36 of the apparatus, at that location, relatively thin shims forming pinch rails 38, whose lead edges are tapered toward their supporting guide rails, to thereby gradually pinch the wall panels 10 and 12 towards one another and effect a compression without risk of damage of the carton walls. Substantially simultaneously with the pinching operation, as indicated at position E, pressure is applied, likewise progressively and gradually, to the outer closure flap 16, from the exterior, to press all of the flaps together to form the seal; the pressure being applied only slightly behind the application of the pinching pressure by the pinch rails 38. Such pressure application may be in any conventional manner, as by means of a pressure plate 40, shown in the drawings in broken lines, for clarity of illustration, or by rollers. Preferably the degree of pinching is relatively slight, totaling approximately one-sixteenth of an inch or & inch on each side.

It may be here stated that the shims 38 may be per- 'manently coated with a plastic lubricant of the type that is frequently used on the guide rails themselves, to reduce the friction on the cartons moving between them.

The pinching rails 38 gradually and simultaneously form a trough-like recess at the edge of each of walls 10 and 12, extending their entire width (FIGS. 4 and 5) as the carton advances between them, which recess encloses the marginal side edge portions of inner dust flaps 22 and 24 to support the glue-wetted dust flaps against curling inwardly and separating from the overlying end wall flap. The pinching rails 38 also serve to bring the upper edges of the front and rear walls 10 and 12 into contact with the line of thickened adhesive 32 which is pressed from between the adhesive-coated flaps under pressure of plate 40, at least at the points at or adjacent the corners of the carton, even when flaps 22 and 24 are not entirely parallel to walls 10 and 12, to assure the filling in and sealing of such corners by a direct adhesion between the sides 10 and 12 wth the edges of flaps 22 and 24 and thereby produce a sealed end closure for the carton which is siftproof.

This completes the description of the method of the present invention and of the resultant product. It will be readily apparent that the method of the invention is particularly advantageous for the sealing of the open end of a filled carton, whose complete and siftproof sealing may not be assured by conventional methods. It will be also apparent that the method of the present invention wZll produce cartons of standard shape and character that will be 'fully sealed at their ends and completely siftproof. It will be additionally apparent that the method of the present invention will not only provide cartons whose contents are preserved against sifting out of the carton, but will also preserve the flavor, if any, and the freshness of the contents and will protect the contents against the intrusion from the outside of any deleterious substance, fumes or vermin.

It will be further apparent that numerous modifications and variations may be made to the method of the present invention, in accordance with the principles of the invention hereinahove set forth, and without the exercise of any inventive ingenuity. I desire, therefore, the protection of the patent laws for any and all such modifications and variations that may be made within the spirit of the invention and the scope of the claims hereto appended.

What I claim is:

1. In the process of sealing the end of a carton having end wall-forming dust flap and closure flaps each connected to a Wall of the carton and including the steps of applying the sealant material to the surface of selected of said flaps for adhering them together when in overlapping position, moving said flaps into overlapping position and applying pressure over said flaps when in said position to adhere them together, the steps of moving said carton past rigidly fixed pinching rails arranged to engage against the closure flap connected side walls of the carton closely adjacent to their junction with their closure flaps to thereby gradually apply pinching pressure against said walls, said pressure being simultaneously applied from one edge of the carton to the other, thereby forming a trough-like recess at each said junction along the entire juncture and enclosing and supporting the marginal edge portions of the adjacent of said dust flap-s; and substantially immediately thereafter applying said sealing pressure over said flaps gradually and continuously in the same direction while maintaining said pinching pressure on said walls.

2. The process of claim 1 wherein said pinching pressure and said sealing pressure are both maintained until a bond is formed.

3. The process of claim 1 wherein said pinching pressure is applied sufficiently to reduce the distance between said wall panels about two thirty-seconds of an inch at the point adjacent said junctions.

4. The process of claim 1, also including the step of applying a thickened band of sealant material to said sealant-coated flaps along the marginal portions of their edges adjacent said wall panels.

References Cited UNITED STATES PATENTS 1,094,451 4/1914 Martin 53-374 2,524,032 10/1950 Back 53-47 1,974,256 9/1934 Bergstein 53-47 689,474 12/1901 Fales 53-374 2,916,865 12/1959 Anderson 53-379 2,266,054 12/1941 Lowey et al. 53-387 3,000,163 9/1961 Bellamy 53-387 THERON E. CONDON, Primary Examiner H. M. CULVER, Assistant Examiner 

